Exam 15: Vertebrate Beginnings: the Chordates

Lancelets belong to the subphylum _________.

The most likely candidate for the vertebrate ancestral stock is something similar to the ____________.

"Sea squirts," the most common kind of tunicate,belong to the class __________.

Of the four chordate hallmarks,adult tunicates have only one,the ____________.

During the evolution of the vertebrates,gills changed from respiratory organs to filter-feeding structures.

All chordates have

The __________ were jawed fishes which lived at the same time as the placoderms that may have been the ancestors of today's bony fish.

Cephalochordates have an open circulatory system,and also have a simple heart. Multiple Choice Questions

The post anal tail is seen in humans only as a vestige;the

In vertebrates,pharyngeal gill slits are formed by inpocketing of ectoderm and outpocketing of the endoderm.

A notochord is present at some time in the life cycle of all chordates.

The nerve cord of chordates is solid and dorsal to the alimentary canal.

Chordates probably evolved from the echinoderm-hemichordate assemblage.

The development of a _____________ life style by the early vertebrates is believed to have been key in the success of this group.

Vertebrate animals have